Saturday, October 10, 2015

QHY6 for guide rescue

QHY6 camera
I must say I like off-axis guiding during astrophotography. It provides uncompromised stiffness, but at some cost. Off-axis guider field of view is very modest, and sometimes it is not so easy to find bright enough star to hook on. That's why quite sensitive and preferable cooled camera is wanted for OAG. Using ASI120 I was happy almost in all cases except a few when I needed to reframe my picture to find a star to guide. So I decided to test QHY6 camera in that role also sold at ALccd-QHY6 name by astrolumina.de . 
Compared to ASI120MM
Camera is equipped with peltier cooling that drops sensor temperature about 24C below the ambient. Neither cooling power nor temperature cannot be controlled. Cooling fan is very quiet, and temperature stabilizes quickly. Camera drivers at both 32 and 64 bit windows machine have been installed without any problem, and camera has started at first connection. Camera drains 0.3A from the 12V power supplier, so it is not power hungry.
First night tests showed that camera is quite sensitive. 5 seconds exposure with TS13/910 refractor recorded stars as faint as 15mag. Stars brighter than 14.5mag has SNR better than 10, so they can be used for guiding.
5 seconds exposure with QHY6 camera
I am quite happy with the camera sensitivity, comparing to ASI120MM it is better about 2.5-3mag. It is especially obvious when ambient temperature is quite high. 

Pros:

  • it is small and lightweight
  • does not require much power 
  • can be supplied only with 5V from USB port (then it is not cooled)
  • it is fast (USB2) so image is beeing read quickly
  • no problems with windows 7 32 and 64 bit
Cons:
  • it is interlaced camera, so saturated images needs to be deinterlaced
  • pixel is not square - 6.5x6.25um
  • there is no control for colling - on or off
  • sensor chamber is not sealed, so frost can occur at high humidity (over 90%). Hovewer there is a place in camera body to put dessicant bag
Sample bias frame

Sample 300s dark frame
Clear skies!

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